


your smile lights up my world

by AQueenWithoutRules



Series: The Undertale Brothers, and How They Came to Be [10]
Category: Undertale (Video Game)
Genre: Childhood Romance, F/M, First Kiss, Fluff and Angst, Fontcest, M/M, Origin Story, Origins, implied fontcest, kiss, sfw
Language: English
Status: Completed
Published: 2017-03-25
Updated: 2017-03-25
Packaged: 2018-10-10 08:00:26
Rating: Teen And Up Audiences
Warnings: Major Character Death
Chapters: 1
Words: 1,729
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/10433049
Author URL: https://archiveofourown.org/users/AQueenWithoutRules/pseuds/AQueenWithoutRules
Summary: Sans originally had a crush on Goner Kid.  So, the question is, what changed?Child happy romance that ends in bad stuff





	

**Author's Note:**

> Uh I don't even know if I should actually count this as part of my little Undertale origin series because I had no plans for this originally so if you find a plot hole there is a very obvious reason  
> I don't even know if GK x Sans is a pairing that people think of my bad  
> There's just the stuff about GK being a Gaster follower and if Sans was technically a Gaster follower too??  
> ????  
> Warnings now for Sans maybe subconsciously using Papyrus to cope all this time idk  
> I did not plan this and i am tired  
> Takes place just before the Gaster incident, if you wanna consider this canon to my dumb little series despite the fact that there are probably a lot of plot holes

Your smile lights up my world

Sans swung his legs happily off of the edge of the Core. GK was sitting next to him, staring off into space. She swayed slightly from side to side.

Gaster warned him to stay away from the edge, along with GK's parents it seemed, as she was always telling Sans not to tell her parents about their being there. They never told anybody about how they would go anyways. Not even MK, GK's sister, no matter how much she asked them. 

The skeleton glanced at the girl to his right, blushing a bit. Freckles dotted her face, and her expression was blank. He smiled, turning his head back toward the Core. If she'd had a hand, sticking out of her striped sweater, he would have been unable to resist grabbing it.

There was some strange thrill about being here alone. Sitting on the edge of what was more than likely death. Nobody knowing where they'd gone. If they both were to fall together, there would be nothing to tell how they'd vanished. No dust to be spread for a funeral.

He didn't quite know why, but the idea excited him.

The comfortable silence continued, and Sans was about to break it before she spoke. Her voice was so soothing. Her head tilted at him, and he tried to orient himself to understand what she had just said. 

“Sans...? I'm curious.”

“y-yeah?”

She pursed he lips, looking down at the lava again.

“Do you... like your brother?”

“like him?” His hands shook, and he pressed them to the ground. Was this a test? What was he supposed to do to pass...? “i- um. yeah...? he's my bro. i love him.” His head tilted in turn. “why?”

One of her feet slammed slightly sharper against the rocks they sat on, allowing a few to fall to the magma below. “I just... He's so annoying!” Her voiced was laced with a desperation and anger that Sans hadn't ever heard out of her. She continued glaring downward. “He's not likable at all. Besides that, you treat him like he's worth everything in the world, but he doesn't do anything to deserve it! You ignore me in favor of him-” She stops talking suddenly, clenching her teeth. “I.... I don't want to be forgotten. I don't want you to choose him over me. But it's so selfish. I know-” 

She's cut off once more as Sans leans in and kisses her.

Everything fades for both of them, white surrounding the corner of their visions as they looked at each other, pulling back from the kiss.

Sans stared at her intensely.

She blushed orange. His favorite color. Her knees came up, hiding her face as she mumbled into them. “I-I d-didn't know y-you...” She didn't continue. Couldn't seem to.

“d-do you feel the same...?” His soul glowed in his chest, pounding so harshly he thought she could hear.

“I-I... I don't- I mean-” Her hesitation apparent, Sans sat back with a sigh. Both of their legs sat still against the side of the cliff. His energy was gone.

“I... I think I might.”

He bolted up straight, turning back to her tensely. Her eyes were wide, and she seemed to be trying to look anywhere but his face as she continued, flushed. Her legs had picked up motion again, swinging against the rocks anxiously. It was cute. Different from her regular actions. “I mean. Maybe? I don't... I can't understand why I feel so scared of you forgetting me. It would only make sense... So...” She turned to him awkwardly. “Maybe I do love you.”

He felt like he'd been struck with arrows, and he smiled brightly, blue blush on his face as his eyelights formed into adoring hearts. He jumped to his feet, dancing around in happiness. The words echoed in his mind, and he looked down at her, jumping in place as he reached his arms out to help her up next to him.

A crack was heard.

Sans looked down at his hands in confusion, as if they had caused it.

GK found the real answer first.

“Sans! Move!” From her seated position, she headbutted him away with an unbalanced roll. He fell on his back. 320/340 HP. But it didn't matter to him at that moment. He rose as soon as he could, but it was too late.

Her eyes laced with fear as the rock she laid on fell towards the lava. “GONER KID!” Sans screamed out for her, reaching his arms out in an attempt to save her. 

He barely caught her by the neck of her sweater. She let out a choking gasp as he tried to pull her up, her feet scrabbling at the rock wall. Her eyes flickered down and back up again, blown wide in a terrified expression. 

Sans was sliding closer to the edge with each passing moment.

Her gaze turned dull as she noticed. Her grey eyes looked up to him, and she managed to adjust herself to speak without choking. “Sans. Let me go.”

He didn't respond, effort renewed as he tried harder to pull her up, simply sliding more.

“Sans.”

He panted with exertion, and tears flooded out of his eyes. If only he had more control over his magic. He could just use blue and everything would be alright...!

“Sans!”

He was snapped out of his stupor slightly, but his flow of tears only increased at her resigned expression. “i can't d o that...!”

She smiled up at him sadly. “Fine then. Just...” A shuddering sigh left her body. “Don't forget me, alright?” And she twisted her head suddenly, writhing in the air as she bit at one of his hands. He released her with a hiss of pain, noticing immediately what she had done and shooting his hands toward her again, unable to catch her as she fell.

Her skin turned grey in the lava, and she didn't scream. He didn't see her turn to dust as she sunk downward.

He pulled himself back from the edge, scratching at his skull almost hard enough to make marks.

Sans felt his health dropping. It was dependent on multiple things. Mostly... hope for the future.

CHECK-  
HP - 1/1

He let out a chuckle.

It turned maniacal.

Nobody had known they were there. 

It had been his fault, for continuing to come here with her.

If only they'd chosen a different meeting spot!

A safer one!

But it was too late now.

He stared at the lava with a new fear. It overtook his body, and he sat paralyzed for a long while.

Eventually he managed to rise.

He held himself, arms close to his chest as his eyes darted from side to side, staying in the middle of the path.

He made it to the Lab. Gaster exited the moment he arrived. He couldn't carry himself anymore. He collapsed into his father's arms, falling asleep instantly.

He woke slowly. The worried voices of two monsters and his father roused him. He gazed blearily at the two, recognizing them as GK's parents, just by appearance. 

The thought of her brought tears to his eyes again, and he let out a sob, attracting their attention. He weakly raised an arm to his face to wipe them, but he couldn't stop them. He was letting out a small stream of “i'm sorry”'s, the parents' worried faces only increasing. 

GK's mother waited for him to slow his cries before responding. “Sans, were you... where is our daughter?”

He couldn't respond coherently. Instead, his sobbing worsened. “i'm sorry-i t-tried to save her- i didn't- i'm so-sorry-i'm sorr-y-”

She covered her mouth with her hands, her own eyes filling with tears as she buried her face in her husband's shoulder. A small voice spoke out, someone Sans hadn't noticed in the room. Intelligent, especially for the age of two, Monster Kid stood on her tip-toes, peering over the bed. “Where'd big thith go?”

Her father finally spoke, a tired voice with barely concealed emotion. “She's not here anymore.”

“Well where'd she go?”

“She... MK, she's died.” 

The child froze. “Died?”

The beat of silence was almost too much for anyone in the room.

“Haha...” Monster Kid's hands clenched the sheets of the bed tightly. “No... sh-she ithn't. She couldn't be. She'th too thtrong for that! She couldn't...” She shook her head. “Right here. She'th right here. Right nextht to me. She didn't leave! You jutht... can't thee her anymore! Sh-she'th.... thtill here...”

And none of them argued with her as she talked to the empty space next to her. How could they...? Sans' consciousness faded out again. When he woke once more, the room was dark and empty. He curled in on himself under the covers. His soul hurt so badly. Why...? He couldn't understand it... He heard the creak of the door opening and couldn't even bother himself to turn his head toward it.

Silence continued before he felt a small body crawling up onto the bed. It struggled to make its way up at first, but once it did it sat on his spine, leaning forward and patting at Sans' face.

His eyes opened to his small-boned brother, who gave him a tooth-gapped smile at seeing him awake. Five years old. He wasn't smart for his age, rather unintelligent in fact, but Sans couldn't bring himself to care. 

'he's so annoying!'

The smile on Papyrus' face made Sans question everything.

Tears leaked out of his eyes again, and Papyrus worriedly patted them away, letting out the incoherent babbling of a child. Sans sat himself up, wrapping his arms around the small body and pulling him close, not letting him go. He felt arms wrap around his body in turn, sobbing into his little brother's shoulder.

He finally pulled him back, tears all along his face that he desperately tried to wipe, but Papyrus wore an understanding smile.

'Unintelligent.'

His face flushed blue and he pushed their foreheads together, laying back down.

The smaller's magic was orange, he noticed as he drifted off to sleep again.

Sans' favorite color.

-

The shadow that had fallen over the doorway at some point finally walked away as the colors in the darkness faded with exhaustion.

10/10 - HP.

Gaster smiled sadly. 

It wasn't good.

But it was better than one.

**Author's Note:**

> Sorry if you couldn't understand MK they are a small child  
> also sans is bi in case that wasn't obvious enough yes  
> Mk had a lot of problems after that. She basically adopted the role of her sister, saying the same things, just to try and fill in the hole in her family, hence the 'don't tell my parents i'm here!' while still imagining that her sister was alive. "My sister says worse stuff than that all the time!"  
> Yeah this chapter isn't fun  
> altho i mean development of Sans' first feelings for Paps so that's ok i guess


End file.
